1. Field of the Invention
This invention relates generally to aqueous dispersions of silicone oils prepared using water soluble and/or water dispersible polymers providing inventive compositions which exhibit a rheological Critical Strain value greater than zero and less than about 0.5. Aqueous dispersions of silicone oils are prepared without the need for surfactants, solvents, hydrotropes or emulsifiers by employing water soluble and/or water dispersible polymers providing inventive compositions which exhibit a rheological Critical Strain value greater than zero and less than about 0.5. Disclosed according to the present invention are compositions and methods of use of the aqueous dispersions of silicone fluids for cleaning, preserving, protecting, and otherwise treating a variety of surfaces, including household surfaces, such as floors, counter tops, furniture, walls, and automotive surfaces, such as tires, rubber, vinyl, upholstery, fabric, plastic and general elastomer surfaces. Disclosed according to the present invention are compositions and methods of use of the aqueous dispersions of silicone fluids prepared using water soluble and/or water dispersible polymers providing inventive compositions which exhibit a rheological Critical Strain value greater than zero and less than about 0.5 and an Elastic Modulus value greater than zero and less than about 400 Pascals.
2. Description of the Related Art
A typical approach in the art for producing stable compositions containing silicones is by forming an emulsified phase or emulsion of the silicone oil in water through the use of emulsifying agents such as surfactants, solvents, hydrotropes and their respective mixtures combined with high-shear mixing conditions to obtain a particle size of the silicone oil small enough for reasonable storage stability and preventing gross separation of the silicone oil droplets resulting in formation of a separate silicone phase. Current equipment and procedures are only able to reduce the average particle size to about 3-10 microns in surfactant-based emulsions, and inherent to high shear processing is the potential degradation of other additives, particularly longer chain polymers, and contribution to localized heating effects during processing that can further degrade heat-sensitive ingredients, such as fragrances, preservatives and the like. Further, high shear mixing processes bring the introduction of unwanted air into the formulation, creating changes in density and leading to problems with reproducibility of the manufacturing process and instability of the product, as well as handling issues due to excessive foaming.
The use of emulsifying surfactants is also problematic with regards to the intended end use of the silicone emulsions, which are employed for cleaning, preserving and protecting surfaces achieved through deposition of the silicone material in the form of a thin coating onto the treated surface. The level of emulsifying surfactant required in the compositions to produce storage stable emulsions are typically large with respect to the level of surfactant required for cleaning action and necessarily must be present at some significantly high ratio with respect to the silicone oil in order to effect a stable emulsion. Thus, some surfactant necessarily remains in the silicone phase deposited on the treated surface resulting in undesirable characteristics both from an aesthetic and functional perspective, particularly since the surfactant employed is advantageously selected for its emulsifying capability rather than another benefit such as for wetting or cleaning purposes. Surfactant based silicone emulsions used in surface treatment applications thus tend to suffer from undesirable characteristics, such as reduced shine, reduced coating longevity, increased susceptibility to hydration by water and/or high humidity, susceptibility to rinse-off by water, increased stickiness to the treated surface leading to dust pickup, retention of fingerprints and the like, owing to the surfactant employed as emulsifier.
Alternative approaches in the art for emulsifying silicone oils include the use of solvents and hydrotropes, alone and in combination with emulsifying surfactants, in order to achieve emulsification of the silicones. Solvents are not without their own issues, for instance those that fall in the class of volatile organic compounds, are subject to ever increasing regulatory compliance issues. While volatile solvents evaporate after application, the resulting films suffer less from the detrimental effects of the correspondingly reduced or replaced surfactant emulsifiers present. However, in general solvents are often flammable, aggressive to the substrates to which the silicone compositions are applied, require special packaging and handling requirements, and limit formulation options such as including other beneficial ingredients to the compositions that are not solvent compatible. Generally, high solvent and/or hydrotrope level and solvents and hydrotropes capable of coupling the silicone oil to water are required, with similar issues to the emulsifying surfactants as described above owing to their incorporation into the resulting silicone film deposited onto the treated surface.
Further, the emulsions formed in prior practice achieve a high degree of stability with regards to storage conditions, temperature and time typically required for practical use. However, the inherent stability of these emulsions can result in lowered performance owing to the inability of the emulsions to break, that is to release the emulsified silicone oils, at time of use so that the silicone oils are available to coat the intended target surface or substrate. It is desirable to coat or treat the surface with a layer of essentially pure silicone oil, or alternatively with silicone oil without significant or otherwise detrimental levels of emulsifying agents, rather than to provide a coating or layer of emulsified silicone oil with extraneous components present that not only do not contribute to the desired protective benefits, but may detract from these protective benefits.
To over come some of the negative effects of the emulsifiers commonly employed, higher levels of the silicone oils are typically required for the formulations to exhibit the desired preserving, protecting and aesthetic benefits to treated surfaces such as those disclosed herein. In essence, a high silicone oil level, typically in amounts exceeding 20% by weight, and often greater than 30% by weight, are usually employed in practice to overcome the poorer performance of the prior art emulsions of silicone oils for these purposes.
Accordingly, there is a need in the art for improved silicone oil based compositions which will provide a beneficial cleaning, protecting, preserving and otherwise restorative effect to surfaces, as well as imparting desirable gloss or shine to a treated surface without the need for extraneous emulsifying or solubilizing materials such as emulsifying surfactants, solvents or hydrotropes.